How one defines themselves with clothes, pronouns, how they carry themselves, etc (i.e. male, female, androgynous, etc). Different from sex- ex: a person may be born female (sex) but identify as male (gender), though for many, sex and gender are synonymous.
"I prefer female pronouns such as 'she' and 'her', because female is my gender." Or "My gender is androgynous, though my sex is male."